The present invention concerns a method and apparatus for displaying images, and more particularly to a method and apparatus for displaying anatomically correlated images.
In the past, physicians have made their diagnoses based on the evaluation of anatomical images displayed on film. These images, once developed on film, were “static” and not easily enhanced by image processing techniques. In addition, film had to be distributed by courier or some other physical means, which added to the delay before the images were available for use by a physician.
Modern Picture Archiving and Communications Systems (PACS) store images in a digital format, which allow physicians greater control over the images and provide the ability for these images to be displayed on high-resolution computer monitors. PACS also provide efficiencies of distribution and storage that were heretofore unavailable with film.
A PACS type of system also allows greater control over which images are displayed, and the physician interface has evolved over the last few years to make image navigation easier and more efficient. Techniques such as “grouping common orientations,” which allows the physician to scroll through multiple stacks of images of the same acquisition orientation (e.g., either in an axial, sagittal, coronal or oblique orientation)concurrently, have become commonplace.
The common orientation grouping technique allows the physician to identify an abnormality in one image, and then confirm the diagnosis in another image from another stack of images acquired at the same anatomic location and orientation but with a different imaging technique or technology. As used herein, a “stack” of images is a sequence of images captured or “acquired” in one session, with all images in the stack having the same orientation. A “series” of images includes one or more stacks, with each stack in the series being acquired using a different technique or technology, but still with all images having the same orientation.
For example, one imaging technique is a double-echo capture, where the same shot is captured at two different times of the same “exposure.” The resulting image series thus includes a stack of images captured at a first time instance, T1 (i.e., the first echo), and a corresponding stack of images captured at a second time instance, T2 (i.e., the second echo). Abnormal cells, such as those belonging to a tumor, image differently from other cells (e.g., the abnormal cells being either lighter or darker than the surrounding cells in images) depending on when the images are taken, and therefore might be easier to identify in one particular series of images. Thus, where the physician sees an abnormality while examining the series of images captured at T1, the physician can view a corresponding image from the series of images captured at T2 to help confirm the diagnosis.
During a medical procedure, know as an “exam,” many series are acquired at different orientations, and with different imaging techniques to demonstrate the anatomy from many perspectives. Each stack of images, whether they differ in being acquired with just a different technique, or a different orientation, may be displayed in a separate window, by which Anatomic Triangulation can be used to synchronize the anatomic region.
The process of identifying a corresponding image in a second stack of images based on a displayed image in a first stack of images is referred to as “image correlation.” The ease and speed of image correlation is very important as it allows the physician to be more efficient in the diagnostic process, in addition to improving diagnostic accuracy. Moreover, the image navigational issues have become critically important due to the large number of images currently being acquired on state-of-the-art medical scanners. Today, it is not uncommon for a computed tomography (CT) or Magnetic Resonance Imaging (MRI) scanner to acquire thousands of images in one session, or “exam,” making image identification and display a significant issue. However, current techniques are based on navigation through stacks of images with only one-dimensional image correlation (i.e., grouping of common orientations) being applied to date. This “1-axis correlation,” used on most image display systems to help-reduce the effort required to evaluate the large number of acquired diagnostic images, is limited to assisting the physician in navigating through corresponding stacks of images, but only where the corresponding stacks of images are in the same orientation.
With cases becoming larger and larger (i.e., more and more images being acquired in each series of captures), physicians are spending more time navigating these large cases and trying to locate corresponding anatomic locations in many acquisition orientations, and impacting the total time they can spend on each case. Accordingly, there is a need for a better system for image correlation.